The recent proliferation of electronic devices for communication, information management and recreation has moved routine computing power away from the desk-bound personal computer. Users are using devices such as cell phones, camera phones, personal digital assistants (PDAs) and navigation systems, not only in the office and in the home, but also in the field and on the road. There is a diverse range of possible applications for such devices, including communication, business, navigation, entertainment and even managing basic daily activities. Many users today only use a single device for a single task, for example, using cell phones for making and receiving phone calls. However, these devices are no longer single-function devices. They are capable of creating various types of data, for instance, electronic mail, voice messages, photos, video, etc. Increasing the number of functions of a device increases the level of personalization to the users. It is desirable to provide users a connected-service to connect and access their data wherever they are, with whatever device they are using and whatever service they are connected to.
A conventional data gateway for handling millions of user devices with different data sources, such as IMAP, POP, WebDAV Exchange, is by employing a server farm with multiple gateway servers. Each gateway server in the server farm maintains a persistent storage for handling job requests of updating changes of users' data. However, this conventional data gateway has a number of problems. One of the problems of the conventional data gateway is to provide failover support. When a server in the server farm fails or is inactive for a period of time, the system needs to transfer the job requests assigned to the failed server to other servers in the farm without losing the job requests. Thus, there is a need for a system that can transfer job requests from a failed server to other servers in the farm seamlessly.
Another problem of the conventional data gateway is to provide a scalable system to support a growing user base. When a particular server farm runs out of capacity, it would be difficult to transfer the persistent storage of job requests to a new server farm as the job requests stored in the persistent storage may be at different stages of processing. Thus, there is a need for a system that can scale as the user base grows.
Yet another problem of the conventional data gateway is to process job requests in an efficient manner. Since a user's job requests are not consistently sent to a particular server in the server farm, the user's account data need to be transferred and cached in multiple servers where the job requests are processed, which leads to additional use of data gateway resources. Therefore, there is a need for a system that can consistently send a user's job requests to a particular server such that the user's account data may be cached and efficiently used for subsequent job requests from the user.